Dogs and coyotes WILL go over an unelectrified 6-ft fence, I've seen them do it.

If you get dogs, keep them where the valuables are. This is obvious to me, but not to many others. They refuse to fence even a portion of the property near the house, and tie the dogs out on a chain. So they bark if someone comes near, big deal. I can walk right past them and get into your house, the dogs are no threat. Dogs loose in a fenced yard are a problem to an intruder; not an insurmountable problem, but might make the difference to a casual intruder.

And don't bother with those underground fences. If your dogs are good enough to be watchdogs, their prey drive will be high enough that they WILL eventually blow right past it and get out of the yard, esp if chasing something, like an intruder. Then the collar won't let him back in the yard, once the excitement of the chase is past. Once they know they can blow through it, it's useless.

Consider an inner fence and a perimeter fence. I've found mine very useful. My home fencing surrounds my house, where I usually keep my dogs, esp when I'm not home. This helps to eliminate poison tossed over the back fence (at one point, my immediate neighborhood had at least six drug houses in it). I can confine the dogs to the immediate back yard, the front yard, or let them run in both. When they're loose, NO ONE comes past the front gate unless the dogs know them. They're not mean, but they put on a good act. I've never been burgled here, even with a meth lab next door, and nearly all the neighbors have had burglaries or stuff stolen from their garages or yards.

Sue